Subject: Re: [Xen-devel] compound skb frag pages appearing in start_xmit

From: ANNIE LI <[email-masked]>
Date: Thu, 15 Nov 2012 10:31:42 +0800

On 2012-10-11 18:14, Ian Campbell wrote:
> On Thu, 2012-10-11 at 11:05 +0100, Eric Dumazet wrote:
>> On Thu, 2012-10-11 at 12:00 +0200, Sander Eikelenboom wrote:
>>
>>> Probably due to the BUG_ON from the patch below, i changed it into a WARN_ON.
>>> And i seem to hit it, but only in one of the guests at the moment and it triggers quite irregularly.
>> xennet_make_frags() is able to split the skb->head in multiple page-size
>> chunks.
>>
>> It should do the same for fragments
> Right, I just want to be reproduce the issue so I can know I've fixed it
> properly ;-)
Hi Ian,

I can reproduce this BUG_ON when running netperf/netserver test between 
two domus running on the same dom0. The domu and dom0 all use v3.7-rc1.

When I tried to rebase my persistent grant netfront/netback patch on 
latest kernel, netperf/netserver test never succeeded. I did some test 
to find out that v3.6-rc7 works fine, but v3.7-rc1, v3.7-rc2 and 
v3.7-rc4 does not succeed in netperf/netserver test. So I keep my 
persistent grant patch only based on v3.4-rc3 now.

Konrad thought about commit 6a8ed462f16b8455eec5ae00eb6014159a6721f0 in 
v3.7-rc1, and suggested me to test your debug patch in netfront. This 
BUG_ON happens soon after running the netperf/netserver test case.

Thanks
Annie
>
> Ian.
>
>
>
>
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